1. Field of the Invention
The invention relates to a method of manufacturing a muffler and a muffler, in particular, a muffler having a round-cornered polygonal tubular shape and a method of manufacturing a muffler.
2. Description of Related Art
In recent years, a muffler mounted on a vehicle body is required to be able to easily mount while improving performance. Further, the muffler is required to be low cost. Thus, Japanese Patent Application Publication No. 2004-36528 (JP 2004-36528 A) discloses a conventional muffler and an example of a method of manufacturing the same.
JP 2004-36528 A discloses an exhaust muffler that uses a rolled titanium material and a method of manufacturing the same. According to JP2004-36528 A, an inner cylinder member and an outer cylinder member formed by trimming a band of rolled titanium material in a rolled fashion into a predetermined dimension, followed by rolling machining form a muffler. At this time, according to JP2004-36528 A, the inner cylinder member and the outer cylinder member are processed by the rolling machine in a substantially vertical direction to a rolling direction of the rolled titanium material to form a muffler.
However, according to a conventional muffler and a method of manufacturing the same, there was a problem that difficulty during mounting, such as interference between a muffler to be manufactured and a vehicle body, cannot be avoided, because it is difficult to form the muffler so that a shape of a side surface of the muffler fits a vehicular frame.